An autonomous travel technology or a driving support technology that detects information of surrounding environment and performs estimation and control of a traveling state is developed for the improvement of convenience and safety of a moving body such as a robot or an automobile. Various sensors are used for detecting information of the surrounding environment. In general, a camera, a laser sensor, a millimeter wave radar, or the like is used as a sensor for measuring the surrounding environment and a Global Positioning System (GPS), an Inertial Measurement Unit (IMU), or the like is used as a sensor for measuring the position of a moving body.
In autonomous travel, the surrounding environment is measured while estimating the moving body's own position (the so-called “self-position” or “ego-position”) by integration of velocity and angular velocity calculated by the IMU or GPS, the position of a landmark or an object which becomes a reference position is detected by the laser sensor or the camera, and a route for target route follow-up or for avoiding obstacles is generated.
In generating the route, a moving body which travels on a road needs to travel inside a lane defined by a white line or the like on a road and thus, it is important to detect the lane with high reliability. In general, the lane is detected using a camera and the white line may not be detected depending on an environmental condition. Several methods for estimating the position of undetected white lines have been proposed.
For example, in PTL 1, an image processing method which is characterized in that a road end of a road area is detected from an image captured by an image capturing unit and an undetected white line is estimated from a road end line estimated from the detected road end and parameters of road design is disclosed. In this technology, in a case where the white line cannot be detected from the captured image, the road end of the road area is detected from the captured image, the road end line is estimated from the road end, and the undetected white line is estimated from a vanishing point of the road end line and design parameters of the road. Here, the vanishing point is a point that when lines which are parallel in the real world are observed from a certain point, the lines are viewed as being terminated at one point. Furthermore, in this technology, in a case where the road end line cannot be detected, parallel lines of feature points such as a reflection plate of a guard rail, trees, or the like are estimated and the undetected white line is estimated using the vanishing points of parallel lines of feature points. With this, even in a case where it is unable to detect the white line in rainy conditions or the like, it is possible to estimate the undetected white line.